Non-aqueous Pickering Emulsions Stabilized By Ionic Liquids Functionalized Janus Materials

Janus materials have many special properties due to its asymmetric chemical structure, and are consequently considered as one of the most attractive kind of materials. In this article, Janus sheet and Janus snowman composite particles modified by ionic liquid functional groups was prepared for stabilizing non-aqueous emulsion which is formed by oil phase and hydrophilic ionic liquid phase. The compatibility between ionic liquid functional groups and bulk ionic liquid phase was proved to be important for obtaining stable emulsion. The present work provides a new strategy for conducting anhydrous reaction in emulsion system as the water phase in traditional water-oil emulsion system could be avoid.The main research contents of this thesis are as follows:(1) Paraffin@silica core-shell spheres were obtained through the emulsion interface self-assembly method and sol-gel reaction. Afterwards, Janus hollow spheres with imidazolin groups and phenyl-groups located at the outer and inner side, respectively. The corresponding Janus nanosheets were obtained by mechanically crushing the Janus hollow spheres. The imidazolin groups were further ionized to get ionic liquid functional groups with Cl" as anion, while the lipophilic phenyl groups were retained. "Oil-Hydrophilic ionic liquid" emulsion was formed by employing the ionic liquid functionalized Janus nanosheets as Pickering type emulsifier, and the impact of the Janus sheet surface wettability, the composition of oil phase, the ratio of oil phase and hydrophilic ionic liquid phase and the amount Janus sheets on the properties of the emulsion were discussed. It was found that the introduction of ionic liquid group is important for fabricating stable ionic liquid based emulsion. The Janus nanosheets can also applied on emulsions with different oil composition including toluene, hexane, octane, dodecane, etc. The emulsion type (IL/O or O/IL) is influenced by ratio of oil phase and hydrophilic ionic liquid phase. Additionally, the amount of ionic liquid functionalized Janus nanosheets can make effect on the average emulsion droplet size.(2) Snowman like silica@PDVB(polydivinylbenzene)/PS(Polystyrene) Janus composite particles were prepared by seed emulsion polymerization, the hydrophilic silica part phase and hydrophobic PDVB/PS phase were separated due to incompatibility after polymerization. And then the selective surface modification was conducted to incorporate imidazolin groups onto silica bulge. Whereafter, more hydrophilic Cl- based ionic liquid functionalized particles were obtained via ionization of imidazolin groups, while the lipophilic polystyrene part was not affected. Subsequently the ionic liquid functionalized Janus snowman composite particles were used to emulsify "oil-hydrophilic ionic liquid" mixture to fabricate stable emulsion, and the impact of the Janus snowman composite surface wettability, the composition of oil phase, the ratio of oil phase and hydrophilic ionic liquid phase and the amount Janus snowman composite on the properties of the emulsion were discussed. It was found that the introduction of Cl- ionic liquid group can enhance the hydrophilicity of silica side of Janus snowman composite particles, and consequently improved stability of the corresponding emulsions, irrespective of oil phase composition. The emulsion type (IL/O or O/IL) was influenced by ratio of oil phase and hydrophilic ionic liquid phase. Additionally, the amount of Janus snowman composite particles can affect the emulsion droplet size.